Currently the block layer op_is_write, bio_data_dir and rq_data_dir helper treat every operation that is not a READ as a data out operation. This worked surprisingly long, but the new REQ_OP_ZONE_REPORT operation actually adds a second operation that reads data from the device. Surprisingly nothing critical relied on this direction, but this might be a good opportunity to properly fix this issue up.
We take a little inspiration and use the least significant bit of the operation number to encode the data direction, which just requires us to renumber the operations to fix this scheme. Signed-off-by: Christoph Hellwig <[email protected]> --- include/linux/blk_types.h | 38 ++++++++++++++++++++++++++++++-------- include/linux/fs.h | 5 ----- 2 files changed, 30 insertions(+), 13 deletions(-) diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index dca972d..70d0ef1 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -131,20 +131,37 @@ struct bio { /* * Operations and flags common to the bio and request structures. * We use 8 bits for encoding the operation, and the remaining 24 for flags. + * + * The least significant bit of the operation number indicates the data + * transfer direction: + * + * - if the least significant bit is set transfers are TO the device + * - if the least significant bit is not set transfers are FROM the device + * + * If a operation does not transfer data the least significant bit has not + * meaning. */ #define REQ_OP_BITS 8 #define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1) #define REQ_FLAG_BITS 24 enum req_opf { - REQ_OP_READ, - REQ_OP_WRITE, - REQ_OP_DISCARD, /* request to discard sectors */ - REQ_OP_SECURE_ERASE, /* request to securely erase sectors */ - REQ_OP_WRITE_SAME, /* write same block many times */ - REQ_OP_FLUSH, /* request for cache flush */ - REQ_OP_ZONE_REPORT, /* Get zone information */ - REQ_OP_ZONE_RESET, /* Reset a zone write pointer */ + /* read sectors from the device */ + REQ_OP_READ = 0, + /* write sectors to the device */ + REQ_OP_WRITE = 1, + /* flush the volatile write cache */ + REQ_OP_FLUSH = 2, + /* discard sectors */ + REQ_OP_DISCARD = 3, + /* get zone information */ + REQ_OP_ZONE_REPORT = 4, + /* securely erase sectors */ + REQ_OP_SECURE_ERASE = 5, + /* seset a zone write pointer */ + REQ_OP_ZONE_RESET = 6, + /* write the same sector many times */ + REQ_OP_WRITE_SAME = 7, REQ_OP_LAST, }; @@ -194,6 +211,11 @@ enum req_flag_bits { #define bio_set_op_attrs(bio, op, op_flags) \ ((bio)->bi_opf |= (op | op_flags)) +static inline bool op_is_write(unsigned int op) +{ + return (op & 1); +} + static inline bool op_is_sync(unsigned int op) { return (op & REQ_OP_MASK) == REQ_OP_READ || (op & REQ_SYNC); diff --git a/include/linux/fs.h b/include/linux/fs.h index 16d2b6e..e3e878f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2499,11 +2499,6 @@ extern void make_bad_inode(struct inode *); extern bool is_bad_inode(struct inode *); #ifdef CONFIG_BLOCK -static inline bool op_is_write(unsigned int op) -{ - return op == REQ_OP_READ ? false : true; -} - /* * return data direction, READ or WRITE */ -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
